Human herpesviruses-6,-7 and-8 in organ transplant recipients

The newer herpesviruses are being increasingly recognized as significant op portunistic pathogens in organ transplant recipients. Published data suppor t the role of human herpesvirus-6 as a potential cause of encephalitis and bone marrow suppression in transplant setting. An association of human herp esvirus-6 with fungal infections and cytomegalovirus infection has also bee n documented. Human herpesvirus-7 also appears to be an immunomodulatory ag ent and may facilitate the pathogenicity of cytomegalovirus. Unlike human h erpesviruses -6 and -7, human herepsvirus-8 is not ubiquitous; its seroprev alence exhibits wide geographic variation. Human herpesvirus-8 has been cau sally associated with post-transplant Kaposi's sarcoma. The complete spectr um of pathogenicity and ultimately the effective prophylaxis and management of these viruses has yet to be fully elucidated.